Freshwater fluxes and variability in the Arctic Ocean and subarctic North Atlantic
As salt is largely conserved in the oceans globally, the only way to change the ocean salinity, which is key to many ocean processes by setting density stratification, is by adding or removing fresh water. Significant freshwater changes have recently been observed both in the Arctic Ocean and the su...
| Main Authors: | , , , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2019
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/56630/ https://hdl.handle.net/10013/epic.34930350-6b98-4033-b73a-1e61e0ba8ab8 |
| Summary: | As salt is largely conserved in the oceans globally, the only way to change the ocean salinity, which is key to many ocean processes by setting density stratification, is by adding or removing fresh water. Significant freshwater changes have recently been observed both in the Arctic Ocean and the subpolar North Atlantic. From observations between 1990 and 2013, we found a distinct anti-correlation of the freshwater anomalies in the upper Arctic Ocean and the subarctic North Atlantic (SANA) with anomalies of almost the same magnitude. Analyses of freshwater fluxes from the global Finite Element Sea ice Ocean Model (FESOM) and the Common Ocean-ice Reference Experiment version 2 (CORE-II) atmospheric forcing data set suggests that the freshwater variations in the two regions largely result from changing advective freshwater transports. Variations in the Arctic freshwater export to the North Atlantic are found to be most important for the total freshwater content variability of the upper Arctic Ocean and for the liquid freshwater content variability of the western SANA. The eastern SANA freshwater content seems to be mainly influenced by the exchange with the subtropical North Atlantic. Furthermore these changes are correlated with large-scale atmospheric pressure and circulation patterns. Based on regression analysis we isolate two distinct patterns of sea level pressure with one being associated with the southward volume transport through the Canadian Arctic Archipelago and the other with the southward volume transport through Fram Strait. We propose, that the recently observed rapid changes of freshwater content in the SANA and upper Arctic Ocean resulted from an interplay of these two driving patterns causing parallel changes in the freshwater export on both sides of Greenland. According to our freshwater content time series and the present sea level pressure pattern, the fresh water that accumulated in the Arctic Ocean during the previous decades has started to be released into the SANA in the most recent ... |
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